Someone asked for it so I thought id give this a shot since i know a little bit about the subject.

Glossary for common networking terms:

Hub - Your basic networking device for the connection of multiple computers, also the most inexpensive device on the market. Not advisible for large amounts of computers as it is not segmented and does not prevent collision domains. The basic consumer hub contains around 4-5 ports for basic networking use.

Repeater - Powered/Unpowered device completely designed for the singular purpose of making data reach longer lengths. Both wired and wireless repeaters are sold in order to create a larger radius for data to travel from the root station.

Bridge - I was debating whether to put this in, but it is still somewhat today, especially in wireless networks, so I decided it was noteworthy. The main function of a bridge is to split a LAN into two segments, therefore cutting down collision domains and data flooding significantly, which consequentially saves network bandwidth. These devices use MAC source and destination addresses to determine whether a data frame should pass through the bridge onto the other segment of the LAN. Relatively inexpensive, though not seen in such wide use as switches or hybrids. Switches do this job with multiple ports, hence the reason why these are not seen in wide use anymore. Also, as noted by zman, bridges are also used in the connection of different data types as a type of adapter.

Switch - Slightly more advanced networking device for the connection of multiple computers and very common in use, though still operating on the Data Link layer for those of you who know of the OSI layers. These in a sense are "intelligent" hubs or multi-port bridges, in that they can determine the source and destination address for each packet that passes through. As a result, bandwidth on the network is greatly conserved, compared to the network data spamming of a hub. The price difference is generally very minimal to that of a hub. Basic switches usually entail 4-8 Ports.

Router - Now on this issue I would like to make clear a glaring difference between products marketed as "routers" and those that are truly routers. What you see in stores are not routers in the truest sense of the word, they are hybrids of routing and switching technology, in that they allow multiple connections just like a switch while still creating a segmented, ip-routing based, network. It is also worthy to note that these devices determine packet source and destination through IP addresses, not MAC addresses as is the case with lower level networking devices. A true router, as in a Cisco catalyst 5500 series for example, performs only the functions of a router. It does not allow direct ethernet connections like a hybrid. It is designed to segment multiple networks through gateways, which is what the internet basically is. Commerical users are the prime users of true routers as they often have to segment large numbers of networks and route data between them accordingly. Also, hybrids are usually the most expensive part of the network, but they are useful. I wont get into the prices for true routers

NIC - Network Interface Card. This card is the networking card that your PC uses to connect into a network. It will likely have an ethernet port on the back and if sold within the last 6 years or so it should have both 10/100 Mbps modes for ethernet.

--Wireless Definitions--

WIC - Wireless Interface Card. Same idea as above except it will likely have an antenna sticking out the back for reception of an 802.11a/b/g signal assuming its a PCI card. If its a USB based card, then it will likely just be a device with an antenna sitting on your desk.

802.11a - Designed as an alternative to 802.11b. Supports a maximum of 54mbps, you'll get half. Expensive equipment, unusual signal band making the future standards NOT backwards compatible. No interference from 2.4 ghz devices like cordless phones. This standard will most likely stay in the shadows due to its signal band (5.4 ghz) making it incompatible with both b/g standards.

802.11b - EXTREMEMELY popular and well versed standard for wireless networking. A good majority of all hotspots are operating on this standard. One will find the cheapest equipment if your willing to settle with 802.11b as its so widespread. Maximum thoroughput is 11 Mbps, you'll get half. It is noteworthy to mention that the majority of home broadband connections only put out a maximum of 1.5 Mbps so it is the choice for internet sharing.

802.11g - A wireless protocol in the 2.4Ghz band which can provide up to 54Mbps raw throughput. 802.11g is designed and marketed as a faster direct replacement for 802.11b, and is backward compatible with it, though at some cost in performance. This standard will be the future generation of wireless devices as 802.11b is eventually phased out.

AP/WAP – An Access Point in its simplest form is essentially a wireless hub. It serves to allow wireless clients to connect to a wired LAN as well as to each other. An AP in Access Point Mode cannot wirelessly negotiate its own connection to the LAN; it must be hardwired to a switch or other node. Many access points can be configured for use as an Access Point, Bridge, Multi-point Bridge, Repeater, or Wireless Client.

Multi-point Bridge – A scenario in which three or more access points form a dedicated wireless link between themselves. Serves to wirelessly join separate LAN segments. Each access point must be set to multi-point bridge mode.

WPA - WiFi Protected Access. A key exchange authentication technology drafted by the WiFi Alliance prior to ratifying the more complete 802.11i security standard. Implementing WPA requires a RADIUS server to manage keys, which can then easily scale upwards to manage a large number of users.

SSID - Service Set Identifier. This is the ID for your wireless network, all devices within the network should have the same SSID in order to connect with each other.

--Common networking terms--

Ethernet - The networking standard for basic home use today. Corperate entities and other backbone entities on the enternet transfer over to ATM for the scalability offered, as zman noted. Originally started as a 10 Mbps data layer, it now supports up to 1000 Megabits per second through gigabit adapters, fiber optics etc. High level network protocols such as IP use the ethernet medium.

Bandwidth - Basically this is the data rate that a network can support. Bandwidth is most commonly expressed in bps, or bits per second. NOTE: I have seen tons of people make this mistake. Do not think that a 100 Mbps ethernet connection means 100 megabytes per second, the key word here is bits. Fast ethernet will transmit at a max of 100 megaBITS per second, which is why you never see a rate you might expect. 1 byte = 8 bits. Average broadband connections operate at a rate of anywhere between 1 Megabit a second to 1.5 megabits per second, some are lower.

Half-Duplex/Full-Duplex Mode - Half duplex mode is where a device can only transmit or recieve at one time, where full duplex mode allows a device to transmit and recieve concurrently. For example, two NICs connected by a crossover cable in full-duplex mode with fast ethernet would have a maximum bandwidth of 400 Mbps, 100 to transmit, 100 to recieve for the first NIC and the same for the other. 100 * 4 = 400 Mbps.
If both cards operated in half-duplex mode, the bandwidth would be cut to 200 Mbps.

Patch Cable - Standard straight through ethernet cabling designed to connect computers to routers, switches, etc. Usually in Cat5, though the cat6 standard is out there now.

Crossover Cable - A specialty ethernet cable with a different wire map designed to connect two computers together in a peer to peer NIC connection. It is also in other specialty situations with certain network devices, though it is noteworthy to mention that most network devices built within the last 2 years or so have autosense enabled so that it automatically detects the type of wire inserted, negating the need for this type of cable outside a peer to peer connection.

TCP/IP - Transmission Control Protocol / Internet Protocol - The significant majority of computer equipment now operates on this standard ever since the fading of such older standards like IPX/SPX. All devices connected to the internet operate off an IP network, and the data is transferred through the IP networks by means of the TCP protocol.

IP - I thought that the Internet protocol was worth its own topic. HTTP, UDP, TCP are all formats built off this Layer 3 protocol. IP sends data by means of a packet that contains the header information such as source and destination, and of course the packet data itself. All sources that send packets have their own IP address, a 32-bit number (4 bytes) in the format xxx.xxx.xxx.xxx. Possible numbers range from 0-255. For example, a standard LAN subnet mask is 255.255.255.0, while a standard LAN IP gateway might be 192.168.0.1 or 10.0.0.1.

Subnet - An individual network of IP addresses within a larger network. One could have a main corperate network and have multiple subnets within that network for many private segmented networks.

NAT - Network Address Translation. This is a technology designed for the sole purpose of keeping public IP addresses and private IP addresses seperate. For example, 68.34.234.3 might be my ISP designated public address, but NAT keeps seperate my personal computer address of 192.168.0.2. The main use of this technology is to allow internet connection sharing and enhancement of network security, as it clearly limits the access of external users to my personal computer. It is in ways similar to a firewall, it is found on most gateway devices such as hybrid router/switches for home use.

DHCP - Dynamic Host Control Protocol. This is the protocol that actually allows you to be assigned a private IP address from your hybrid router/switch. Its whole purpose is to allocate private IP addresses for devices connected to it. DHCP is found on a multitude of devices such as PCs, hybrid routers, and a couple other network devices as well. The key thing to remember with DHCP is that in a private unsegmented network, you may only have 1 device playing DHCP server, which is usually your hybrid router/switch.

ICS - Internet Connection Sharing. This is both a term and a windows program designed to share a connection between two windows computers without the use of a router/switch hybrid.

Gateway address - This is the IP address of the device leading you into another network, for example, if your router/switch had an IP of 192.168.0.1, it would be the gateway into the internet, assuming you had a WAN connection such as a ADSL modem, etc.

LAN - Local area network..need i say more.

WAN - Wide area network, commonly used interchangably with the internet, though it could also be any corperate long distance interior network. If something says "WAN port," it is talking about the ethernet connection to your broadband modem.

Port - Essentially a channel for network communications. For example, telnet is port 23. Allowing different ports on a computer allows network applications to all function without interfering with each other. Port numbers can range in the IP protocol from 0 - 65535. Open ports are often spoken about in many discussions regarding hacker attacks, as they can be used to break into a computer, given the right port. Trojan devices often open up their own port for remote access, sometimes a creative number is used such as 1337 or the like.

PPPoE - Point to Point protocol over Ethernet. A common transmission protocol for broadband devices such as ADSL, combining attributes of the standard PPP protocol for windows (originally designed for narrowband modem connections), and the ethernet network.

Ok i know im forgetting stuff, but this should cover the basics, besides my hands hurt

Jim

Last edited by jim021 on Fri Aug 06, 2004 3:56 am, edited 5 times in total.

Essentially, with hubs, only one device in the network can "talk" at any given moment. Switches eliminate that problem.

Not necessarily. A gateway is the final device between your network and the internet. Usually, in most home setups, the router is the gateway. Think of the gate entrance in a wall surrounding a building. Only one way to get in or out.

The "typical wired router" is usually a switch, so you're right there, and those routers are also gateways. So, you've got that too. The "broadband capability" is a marketing scheme, it doesn't mean much.

The best things in life are free.http://www.gentoo.orgGuy 1: Surely, you will fold with me.Guy 2: Alright, but don't call me Shirley.

The term gateways is a generic term. While it is an actual device, they really don't exist much in today's network environment.

Gateways were first developed somewhere in the late 60's early 70's. See there were no standards then, or what few standards started to emerge not everyone was using. So for two systems to communicate to one another a device (computer or server of some sort) was needed in between to translate one type of network protocol to another. They acted like a translator of terminal emulation software, network protocols, whatever so two dissimilar systems were trying to talk they could understand each other.

Granted today standards are in place or software is able to emulate, or understand multiple communication standards. One example would be a VPN device can be called a gateway, since it allows for a encrypted secure connection into a private network. Quite often they are referred to as VPN gateways.

"I used to think the brain was the most amazing organ in the entire body. Then I realized who was telling me this."
If ignorance were painful, half the posters here would be on morphine drips.

jim021 wrote:For example, two NICs connected by a crossover cable in full-duplex mode with fast ethernet would have a maximum bandwidth of 400 Mbps, 100 to transmit, 100 to recieve for the first NIC and the same for the other. 100 * 4 = 400 Mbps.If both cards operated in half-duplex mode, the bandwidth would be cut to 200 Mbps.

That's an odd way to calculate bandwidth: you're double counting the same data stream that one NIC is sending and the other is receiving. Most people would say that sending a 100mbps stream from NIC A to NIC B is "using" 100mbps bandwidth, not 200mbps.

jim021 wrote:Port numbers can range in the IP protocol from 0 - 65535.

Ports are not a part of the IP layer, but the layers above it (e.g. transports like TCP, UDP, etc.). So when you talk about ports, you also have to specify a higher-level protocol to disambiguate. TCP port 23 is different from UDP port 23, etc. As far as the range, it's true that TCP, UDP, and SCTP (and other transports with port numbers) use 16-bit values, but things over IP don't have to have ports at all or they could use some larger number. Of course, there are practical concerns for using more than 16-bits (unix sockets interface with sockaddr_in's 16-bit sin_port field, existing tool support, sparsity of larger tables, use of ICMP if you get way too big, etc.), but there's nothing mandated in IP layer itself about ports.

I think a couple more things need to be added to our Network Glossary.

PAN: Personal Area Network. Technologies like Bluetooth and Wireless USB would fall into this categoryMAN: Metro Area Network. Like a LAN, but bigger physically. A lot of universities and corporations have MANs.

The best things in life are free.http://www.gentoo.orgGuy 1: Surely, you will fold with me.Guy 2: Alright, but don't call me Shirley.

Expensive equipment, unusual signal band making the future standards NOT backwards compatible. No interference from 2.4 ghz devices like cordless phones. This standard will most likely stay in the shadows due to its signal band (5.4 ghz) making it incompatible with both b/g standards.

1. 802.11a is on the 5Ghz band, not the 5.4GHz band. 2. 802.11n is backwards compatible with both 802.11a and 80211b/g, because it operates on the 5GHz and 2.4GHz bands.

I don't think there's a such thing as a Catalyst router either. Few call a WLAN card a WIC, and a DHCP server doesn't necessarily only hand out private IP addresses. ICS can support more than one client. Gateway address explanation skirts around the point. IP and subnet definitions purport a standard, but fail to acknowledge classful subnetting.

The glossary is far from perfect, but it was better than what we had before.

sure it does. I've done it plenty of times. I assume you mean directly from PC to catalyst series whatever.

Direct electrical connections? IE: Incoming electrons (and the packets they make up) go directly to the outgoing port without passing through logical processing? [<-- Edit: This section is 100% nonsense, but shall remain intact so that the post that follows makes sense. ]

Should likely add the 802.11n and 802.11r[oaming] standards to the list.

Last edited by reynolm on Sat Sep 20, 2008 5:57 pm, edited 1 time in total.

Expensive equipment, unusual signal band making the future standards NOT backwards compatible. No interference from 2.4 ghz devices like cordless phones. This standard will most likely stay in the shadows due to its signal band (5.4 ghz) making it incompatible with both b/g standards.

1. 802.11a is on the 5Ghz band, not the 5.4GHz band.

That's not entirely true. At a previous employer, we used 5.4GHz and 5.8GHz PtMP backhaul radios.

Sorry to necro the thread, but a lot of things have changed since 2008.

1)the 60GHz range is used for Personal Area network, and has also been adopted as Wireless HD, since they only work within a single room. Remember, the higher the frequency, the faster the speed, but shorter the distance.

2) GIgE is being supplanted by 10GigE, especially in CLECs/COs.

3) Without boring everybody with the details, OSPF (Open Shortest Path First) is a Link State Routing Protocol. All areas must have at least one interface in Area0, unless you've set up a Virtual Link

4) EIGRP is cisco proprietary, but it's one of the easiest protocols to setup, short of RIP. It's called DUAL, since it uses the best of Distance Vector and Link State

5) NX-OS is the next gen version of Cisco IOS, but it's mainly used in Data Centers at the moment. The syntax is quite different from standard IOS, and it's a;so used in VMWare's Virtual Switch.

6) MPLS (multi-protocol label switching is the new darling in the telco world, even supplanting IS-IS.

The newest OS Cisco uses in Data Centers is NX-OS, which is a different animal that IOS. There are multiple devices, like virtual switches running on VMWare and Hyper-V, incredibly low-latency for commercial/stock markets, and fabric extenders

9) Adtran TA-5000 aggregators feature a 100Gbps backplane, and can handle line cards ranging from VDSL2 to ATM, and 10GigE.

10) The list goes on and on, but unless someone get's upset about me Necro'ing the thread, I'll stop now.

If anyone has questions about routing protocols, major switching topics (especially enterprise core switches) and telecommunications tech, feel free to PM me, and I'll be happy to answer any and all questions.

I used to be a technical instructor (before becoming an network engineer and Telcom employee) and seeing the "light bulb" going off over my students heads once they understood the topics made me full of joy. I can also point you out to a lot of resources so you can practice, without requiring physical hardware.

Although In most cases I would say it's wrong to say that ISIS is being supplanted by MPLS since MPLS is often not a replacemet for the IGP routing, but is mostly used to forward a lot of packets will full separation in VRF's or MPLS-VPN-setups. Not to mention that most setup's at least here, use first an IGP like IS-IS or more-often OSPF to exchange loopbacks in order to get M-BGP up to propagate the VRF routing info and then use MPLS for the actual packet forwarding through core, etc. You are entirely correct in that IS-IS is being depreciated in most designs as far as I've seen though. Although there might be differences on how it is used in datacenters vs Telco setups that I haven't worked with.

I've worked with networks using ISIS only to propagate loopbacks in order to get MBGP up and have the MPLS on that. In the network I'm involved in building right now they did do away with ISIS and use OSPF for the same reason, exchange loopback's dynamically in order to get M-BGP up to have something that can deliver all VRF routing nicely and then hang the MPLS on it. Of course, then you have a ton of other features that are often used on NX-OS if not used outside of enterprise setups... OTV, Fabric Path, MACSec, vPC+, DMVPN, GETVPN, etc, etc.

Also, don't forget about IOS-XE which is and will be the OS for the the lower half of the segment for a time to come. Basically it's a development that bases everything on a linuxkernel and abstracting everything on it as processing. Thus letting you run IOS as a process running on top of IOS-XE then use an underlying API to connect to different other modules. This will enable IOS development to be separate from hardware development. On top of that, IOS-XE enables you do add different modules, like a WLC on top of a normal Switch like a 3650.

Also I think we might pretty soon come up to a turning point where we will be turning to 40Gbit and 100Gbit for all core uses and 10G will only be used for uplinks and redundancy towards edge and lower end distribution points. just about any gear you get today for datacenter use does have capability for 40G and 100G in some capacity already.

Aphasia wrote:Although In most cases I would say it's wrong to say that ISIS is being supplanted by MPLS since MPLS is often not a replacemet for the IGP routing, but is mostly used to forward a lot of packets will full separation in VRF's or MPLS-VPN-setups. Not to mention that most setup's at least here, use first an IGP like IS-IS or more-often OSPF to exchange loopbacks in order to get M-BGP up to propagate the VRF routing info and then use MPLS for the actual packet forwarding through core, etc. You are entirely correct in that IS-IS is being depreciated in most designs as far as I've seen though. Although there might be differences on how it is used in datacenters vs Telco setups that I haven't worked with.

I've worked with networks using ISIS only to propagate loopbacks in order to get MBGP up and have the MPLS on that. In the network I'm involved in building right now they did do away with ISIS and use OSPF for the same reason, exchange loopback's dynamically in order to get M-BGP up to have something that can deliver all VRF routing nicely and then hang the MPLS on it. Of course, then you have a ton of other features that are often used on NX-OS if not used outside of enterprise setups... OTV, Fabric Path, MACSec, vPC+, DMVPN, GETVPN, etc, etc.

Also, don't forget about IOS-XE which is and will be the OS for the the lower half of the segment for a time to come. Basically it's a development that bases everything on a linuxkernel and abstracting everything on it as processing. Thus letting you run IOS as a process running on top of IOS-XE then use an underlying API to connect to different other modules. This will enable IOS development to be separate from hardware development. On top of that, IOS-XE enables you do add different modules, like a WLC on top of a normal Switch like a 3650.

Also I think we might pretty soon come up to a turning point where we will be turning to 40Gbit and 100Gbit for all core uses and 10G will only be used for uplinks and redundancy towards edge and lower end distribution points. just about any gear you get today for datacenter use does have capability for 40G and 100G in some capacity already.

I forgot to mention that 40GigE is already in use, especially in aggregators in Windstream COs. 2 or 3 ports per line card.

And I'm unfamiliar with M-BGP. iBGP and eBGP, yes, but not mBGP. Can you provide me with some links, since I'm obviously ignorant about that particular protocol, and would love to learn more about it.

And isn't NX-OS linux based? I've only taken the one course on it, so I'd like to learn more about it, too. Dave Lammle has made his NX-OS simulator freely available, if anyone wants to tinker with it.

*EDIT*

I also forgot to mention that 24GHz is going to be the next cellular standard. Well, at least that's my understanding. I could easily be wrong about that, though.